President Donald Trump points to the crowd as he and first lady Melania Trump dance at the Freedom Ball in Washington, on Friday, Jan. 20, 2017, at the Washington Convention Center during the 58th presidential inauguration (AP Photo/Mark Tenally)

WASHINGTON (AP) — As President Donald Trump wrapped up the ceremony of his inauguration and shifted to governing, he signaled he intends to move quickly to make a clean break from the Obama administration.

Trump spent his first night in the White House and was slated to start his first full day in office at a national prayer service Saturday morning. The traditional gathering was the last piece of the transition ritual for the new president before he was clear to get to work.

Trump took his first steps in that direction on Friday. Before attending his inaugural balls, he signed an executive order aimed at undermining former President Barack Obama’s signature health care law. The order notes that Trump plans to seek the “prompt repeal” of the law. But in the meantime, it allows the Health and Human Services Department and other federal agencies to delay implementing any piece of the law that might impose a “fiscal burden” on states, health care providers, families or individuals.

Trump also cleared the way for members of his national security team to take their places. He signed legislation granting James Mattis, his pick for defense secretary, a one-time exception from federal law barring former U.S. service members who have been out of uniform for less than seven years from holding the top Pentagon job. The restriction is meant to preserve civilian control of the military. Mattis, 66, retired from the Marine Corps in 2013.

Hours later, Mattis was confirmed by the Senate as Trump watched his inaugural parade from a stand outside the White House. The Senate later confirmed retired Gen. John Kelly to lead the Homeland Security Department. Vice President Mike Pence swore-in both men late Friday.

In a separate step Friday, White House chief of staff Reince Priebus issued a memo aimed at freezing some new regulations and halting ones that Obama’s administration had started.

Trump brought his signature style to the task of governing, sprinkling his comments at three inaugural balls with references to “phony polls,” campaign victories and social media.

“Let me ask you: should I keep the Twitter going?” he asked a cheering crowd of supporters before dancing with his wife, Melania, to Frank Sinatra’s “My Way” at the second of three inaugural balls. “The enemies keep saying, ‘Oh that’s terrible,’ but it’s a way of bypassing dishonest media.'”

On Saturday, Trump was due to attend a prayer service at the Washington National Cathedral, an Episcopal parish with a dual role as a civic gathering place. The cathedral has for years hosted a prayer service for the new president. But keeping the tradition has sparked debate this year among Episcopalians opposed to Trump’s policies.

It’s the latest example of the backlash against religious leaders, artists, celebrities and other participants in events surrounding the inaugural.

While some in the largely liberal congregation objected to hosting the service, Bishop Mariann Budde of the Episcopal Diocese of Washington wrote in a blog post that she shared “a sense of outrage at some of the president-elect’s words and actions” but also she felt an obligation to welcome all people without qualification, especially those who disagree and need to find a way to work together.

Trump was also expected to visit the CIA on Saturday, meeting with members of the nation’s intelligence community. The visit may be fraught with tension. Trump has sharply criticized the nation’s top intelligence officials for their assertions about Russian hacking and leaks about his briefings in the weeks before he was sworn in.

White House spokesman Sean Spicer told reporters before the inauguration that the visit would involve several departments and Trump intended to offer his appreciation for their service to the country.